1. Field of the Invention
The present invention relates generally to a chrominance signal processing circuit and more particularly to a processing circuit of this kind which is suitable for use in demodulation of a wide band chrominance signal.
2. Description of the Prior Art
Recently, various techniques have been proposed for achieving a high resolution, for example, by widening the band of the luminance signal. With such a tendency to require higher resolutions, the definition of color of an image is also desired to be higher.
FIG. 1 shows a frequency spectrum of a composite video signal of the NTSC system. The frequency spectrum is formed of a luminance signal Y and chrominance signals I and Q. As is well known, the luminance signal Y and the chrominance signals I and Q are composed in a frequency interleaved relation.
It can be seen from FIG. 1 that the signal I has a band of 1.5 MHz, and the signal Q a band of 0.5 MHz. If the signals I and Q are reproduced with high fidelity while these bands are maintained, the definition of color of the image can be made high.
Incidentally, the band of a chrominance signal is limited to 0.5 MHz for presently manufactured television receivers so as to get rid of complicated chrominance signal reproducing circuits.
As described above, in order to reproduce the signals I and Q with high fidelity, it is required to widen the band of the chrominance signal separated from a composite video signal. However, so-called wide band demodulation, which is effected by separating a wide band chrominance signal by the use of a comb filter or the like, causes a lot of noise and cross color interference.